Is the soeed of an electron relativistic?

[number14]

Homework Statement

Determine the speed of an electron in a hydrogen atom (radius .5 * 10^-10 m) and state if it is relativistic. (Treat the electron as through it were in a circular orbit around the proton.) (Given that .1c and greater is relativistic)

Homework Equations

not sure...
L=L₀ (1-v^2/c^2)^1/2
a=v^2/r
?

The Attempt at a Solution

I don't really know where to start. I assume the fact that the electron has a centripetal acceleration and velocity comes into play somehow.

 

[number14]

solved it!